Process for converting primary amidoalcohols to amidocarboxylic acids in high yield

ABSTRACT

The invention relates to an improved process for oxidizing a primary amidoalcohol to the corresponding amidocarboxylic acid in high yield.

FIELD OF THE INVENTION

The present invention relates to a process for converting a compound orpolymer comprising a primary alcohol and an amide group toamidocarboxylic acid. In particular, the primary amido alcohol isconverted to carboxylic acid in unexpectedly high yields when propersolvent is selected.

BACKGROUND

Amidocarboxylic acids are desirable surfactants in that they have goodwater solubility, good detergency and foaming properties and are mild toskin and hair. One method for the production of such surfactant isthrough the oxidation of an alcohol containing an amide group (e.g.,coco mono-ethanolamide or CMEA).

The problem, however, is that it is very difficult to drive theoxidation of alcohol to carboxylic acid efficiently. The reaction willoften stop at the aldehyde stage, and the yields of carboxylic acid asfinal products are quite low.

Japanese Patent laid-Open No. 05/194,334 (Sandoz) discloses a process inwhich a hydroxyl containing compound (which may be, for example, alkylamide polyoxyalkanol) is made to react with at least an equimolar amountof inorganic or organic halogen-containing oxidizing agent, e.g. NaOCl,in the presence of weak base and a catalytic amount of hinderednitroxide as exemplified by 2,2,6,6-tetramethylpiperidine1-oxyl,hereafter abbreviated TEMPO, and chemical derivatives thereof. In thispatent, no yield or purity information is given. The process disclosedis limited to alcohols which have polyethylene glycol or polypropyleneglycol substitution, or to polyglucosides, as starting reactants. Suchcompounds are water-soluble or water-dispersible, which makes possiblethe use of water as the solvent. The patent does not teach a processusing hydrophobic primary alcohols (i.e., amido alcohols) of theinvention as starting reactant.

Japanese Patent Laid Open No. 04/283,537 (Shell) discloses a processusing an oxidizing agent such as sodium hypochlorite in the presence ofTEMPO. The process relates to production of an alkoxyalkanoic acid fromthe corresponding alkoxyalkanol, however, and not to the production ofan amidecarboxylic acid from an alcohol having an amide group.

Japanese Laid Open No. 10/087,554 (Lion Corporation) discloses a processfor production of amidocarboxylic acid from alcohol having an amidegroup using an oxidizing agent of chlorine type (e.g. NaOCl) in thepresence of a nitroxide radical (e.g., TEMPO) and further in thepresence of alkali metal halide or alkali earth metal halide (e.g.,potassium chloride). In Examples 3 and 5, for example, an alcoholcomprising amide; a nitroxide radical; and a 10% solution of alkalimetal chloride (potassium or sodium bromide) in water, additional water,and acetonitrile (solvent) are charged into a beaker and stirred. Underthese conditions, the acetonitrile and water mix together to form asingle liquid phase. In each example, the purity of the carboxylic acidis calculated from the acid value, but nothing is stated about yield.The acid value is not selective for the desired carboxylic acid, butwould include all acid components present.

Unexpectedly, applicants have now found that the type of solvent orsolvents used during the oxidation reaction is critical to the yield ofproduct (carboxylic acid). Without wishing to be bound by theory,applicants believe the starting amidoalcohol must not be in the samephase as the oxidizing agent. Applicants have found that this separationof oxidizing agent and alcohol can be accomplished in at least twodifferent ways. According to a separate application applicants havefiled on same date as the subject application, the final product (e.g.,amidocarboxylic acid) is partitioned into an organic solvent (i.e.,using solvent that will form both a hydrophobic liquid phase and anaqueous liquid phase, rather than forming one substantially aqueousphase). In this manner, the exposed amide group on the amidoalcohol isprotected from cleavage (e.g., the bleach which has partitioned mainlyinto aqueous phase will not attack the amidoalcohol in the separatephase), and consequently far greater yield of amidocarboxylic acid isproduced. That is, it is important that, in the presence of theoxidizing agent, both a solvent rich layer (substantially free ofoxidizing agent) and an aqueous layer (comprising substantially of theoxidizing agent) form.

In a second embodiment, which is claimed in the subject application, theoxidizing agent and the alcohol are also maintained in separate phases.Here, however, the two phases are a water phase and a solid phase, andwater alone is used as the solvent. That is, the amidoalcohol, which ishydrophobic, does not dissolve or disperse into the aqueous phase(rather it stays in the solid, non-aqueous phase) while the NaOClremains in the continuous aqueous phase.

As indicated, the subject application relates to processes where wateris employed as solvent and, upon addition of oxidizing agent, theoxidizing agent partitions into solvent while amidoalcohol and/oramidocarboxylic acid stay in solid phase.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a process for converting primary alcoholhaving an amide group to amidocarboxylic acid in high yield (e.g., ≧75,preferably ≧80%, more preferably ≧85%, more preferably ≧90% yield) whichprocess comprises reacting a primary alcohol having amide group(amidoalcohol) with an oxidizing agent, preferably a chlorine-containingoxidant like NaOCl, in the presence of a nitroxide radical andoptionally in the presence of an alkali metal halide or alkali earthmetal halide. In this process the solvent in which the reaction takesplace is selected such that, in the presence of the oxidizing agent, theprimary amidoalcohol partitions or stays (after addition of bleach orother oxidizing agent) in the solid organic phase, while bleach oroxidizing agent partitions substantially into liquid aqueous phase. Suchpartitioning ensues the high yields noted above (e.g., the amide linkageis not available to be cleaved by the oxidizing agent because theoxidizing agent has partitioned into liquid aqueous phase). In otherwords, the amidoalcohol stays in a solid phase and oxidizing agentpartitions quickly enough into the aqueous phase to avoid formation ofundesired by-product. It is completely unexpected that using water assole solvent chosen could make such critical difference.

It is also a critical aspect of the invention that the catalyst used inthis reaction be a hindered nitroxide radical. An optional alkali metalhalide or alkali earth metal halide co-catalyst may also to be used, orthe co-catalyst can be, for example, sodium tetraborate.

Specifically, in one embodiment of the invention, sufficient base (e.g.,sodium hydroxide) is added to the reaction to ensure reaction takesplace at a pH above 6, preferably 7 to 10, more preferably 7.5 to 9,even more preferably 8 to 9. Addition of base is used to make up forconsumption of oxidizing agent (e.g., sodium hypochlorite) duringformation of amidocarboxylic acid. Base may be added to the oxidizingagent solution prior to addition of the oxidizing agent to the reactionor it may be added during the course of the reaction (e.g., to maintainconstant pH).

These and other aspects, features and advantages will become apparent tothose of ordinary skill in the art from a reading of the followingdetailed description and the appended claims. For the avoidance ofdoubt, any feature of one aspect of the present invention may beutilized in any other aspect of the invention. It is noted that theexamples given in the description below are intended to clarify theinvention and are not intended to limit the invention to those examplesper se. Other than in the experimental examples, or where otherwiseindicated, all numbers expressing quantities of ingredients or reactionconditions used herein are to be understood as modified in all instancesby the term “about”. Similarly, all percentages are weight/weightpercentages of the total composition unless otherwise indicated.Numerical ranges expressed in the format “from x to y” are understood toinclude x and y. When for a specific feature multiple preferred rangesare described in the format “from x to y”, it is understood that allranges combining the different endpoints are also contemplated. Wherethe term “comprising” is used in the specification or claims, it is notintended to exclude any terms, steps or features not specificallyrecited. All temperatures are in degrees Celsius (° C.) unless specifiedotherwise. All measurements are in Si units unless specified otherwise.All documents cited are—in relevant part—incorporated herein byreference.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a liquid chromatogram (HPLC) profile of products formed whenreaction was carried out in CH₃CN/water solvent and only a single liquidphase was formed (bottom FIGURE, corresponding to example of JP10/087,554 reference to Lion), compared to when solvent was THF/waterand formed two liquid phases (top).

As observed, a solvent which partitions into two liquid phases leads tohigh yields of N-lauroylglycine (LG) from N-lauroylmonoethanolamide(LMEA) starting material. By contrast, when the organic solvent formed asingle liquid phase with the water, the yield and purity of LG(glycinate) were lower. Thus, for example, the pure LG product waspredominantly formed at 13.54 minutes when two liquid phases formed but,when only one phase formed, there were huge amounts of impurities at15.80 seconds.

DETAILED DESCRIPITON OF THE INVENTION

The present invention relates to a novel and improved process forconverting a primary alcohol comprising an amide group (e.g., C₈-C₂₂alkoylmonoalkanolamide such as lauroyl monoethanolamide) to thecorresponding amidocarboxylic acid (e.g., mixture of N-lauroyl glycineand alkalimetal N-lauroyl glycinate), and which process provides veryhigh yields of product (e.g., ≧75%, preferably ≧80%, more preferably≧85% yield). More specifically the process comprises reacting a primaryalcohol comprising such amide group with an oxidizing agent in thepresence of a nitroxide radical and optional catalyst (e.g., alkalimetal halide), wherein the solvent in which the reaction takes place isselected in such way that two phases separating the amidoalcohol fromthe oxidizing agent are formed. In other words, the amidoalcohol staysor is partitioned into an organic phase of the two phase system therebyand the oxidizing agent stays predominantly in the aqueous phase. Thisprotects the amide group on the amidoalcohol from further cleavage andprovides the high yields as noted. In the specific embodiment of theclaimed invention, the amidoalcohol is separated from the oxidizingagent using only water as solvent in that the oxidizing agent partitionsinto the liquid aqueous phase while the amidoalcohol stays in theundissolved solid state (heterogeneous solid-liquid system).

More specifically, the starting reactant of the subject invention is analcohol having an amide group which may be defined as follows:

R¹—CONR²(CH₂)_(m)OH

wherein R¹ is linear or branched alkyl or alkenyl group having 7 to 22carbon atoms; R² is H, an alkyl or hydroxyalkyl group with 1 to 6 carbonatom(s); and m is an integer from 1 to 6.

Examples of compounds which may be encompassed by the structure areN-alkanoylmonoethanolamines such as N-lauroylmonoethanolamide (LMEA) orN-cocoylmonoethanolamide (CMEA).

The starting product may be a mixture of monoalkanolamides (e.g.,monoethanolamine) including those derived from mixtures of fatty acidsfound in nature. N-cocoyl monoethanolamine, for example may comprise amixture of C₈, C₁₀ and C₁₂ fatty acids as major component mixed withC₁₄, C₁₆ and C₁₈ fatty acids.

The oxidizing agent used to oxidize the starting alcohol can be anyoxidizing agent which will allow the alcohol group to be oxidized tocarboxylic acid. Typically, such oxidizing agents include those of thechlorine type. These may include chlorine, a hypochlorite (e.g., alkalimetal hypochlorite), trichloroisocyanuric acid and dichloroisocyononicacid. Preferred oxidizing agents include sodium hypochlorite (e.g.,industrial grade bleach comprises 5% to 13% sodium hypochlorite),calcium hypochlorite, chlorine itself, and organic chlorine-containingcompounds, for example trichloroisocyanuric acid. Non-chlorinecontaining oxidants may be used, for example, oxone (2KHSO₅.KHSO₄.K₂SO₄), NaOBr, N-bromosuccinimide, or tribromoisocyanuricacid. Non-halogen containing antioxidants may also be used, asexemplified by H₂O₂, optionally in the presence of sodium tungstatedihydrate catalyst.

The amount of oxidizing agent may vary, but typically equimolar to 8molar, preferably 1 to 7 equivalents, more preferably 2 to 6 molar areused.

The starting alcohol of the invention is oxidized with an oxidizingagent (as noted above) in the presence of a hindered piperidinyloxyradical catalyst (nitroxide) and optionally in the presence ofco-catalyst as are described below.

The nitroxide catalyst radical used in the invention (e.g., hinderednitroxide) is produced by oxidation of a cyclic or acyclic secondaryamine containing no α-hydrogens (i.e., there are no hydrogens on thecarbon adjacent to N) with peroxide, or by oxidation of thecorresponding hydroxylamine. Examples of stable nitroxide radicalssuitable for use in this invention are mentioned in the followingdocuments. These include linear, cyclic, dicyclic or macromolecularcompounds to which one or more nitroxyl radicals are connected.

-   Chem. Review, 78, 37 (1979):-   G. Rozantsev, “Free Nitroxyl Radicals”, Penum Publishing    Corporation, New York, 1970; and-   E. G. Rozantsev, V. D., Scholle, Synthesis, 1971, 190.

Preferred examples of the nitroxide radical are as follows.

-   2,2,6,6-Tetramethyl-piperidine 1-oxyl (TEMPO);-   2,2,5,5-Tetramethyl-pyrrolidine 1-oxyl; and-   1-Aza-2,2,7,7-tetramethyl-cycloheptane 1-oxyl.

TEMPO and chemical derivatives thereof are preferred, examples of whichfollow:

-   4-Hydroxyl-2,2,6,6-tetramethyl-piperidine1-oxyl;-   4-Methoxy-2,2,6,6-tetramethyl-piperidine1-oxyl;-   4-Ethoxy-2-2,6,6-tetramethyl-piperidine1-oxyl;-   4-Acetylamido-2-2,6,6-tetramethyl-piperidine1-oxyl;-   4-Carbamoyl-2,2,6,6-tetramethyl-piperidine1-oxyl;-   4-Benzoylamino-2,2,6,6-tetramethyl-piperidine1-oxyl;-   4-Oxo-2,2,6,6-tetramethyl-piperidine1-oxyl;-   2,2,6,6-Tetramethyl-piperidine-1-oxyl4-sulfate;-   2,2,6,6-Tetramethyl-piperidine-1-oxyl4-phosphate; and-   3-Carbamoyl-2,2,6,6-tetramethyl-pyrrolidine1-oxyl.

UV light stabilizers containing 2,2,6,6-tetramethylpiperidinefunctionality (Hindered Amine Light Stabilizers, abbreviated HALS), bothmonomeric and oligomeric, can serve as precursors to stable nitroxylradicals by oxidation as well.

It is also possible that an amine or a hydroxylamine which is aprecursor thereof is used and, in the actual case, it is oxidized andthen used. The amount of the nitroxide radical used to 1 equivalent ofthe starting alcohol material is typically from 0.01 to 10 mol % or,preferably, from 0.1 to 5 mol % based on amidoalcohol.

An optional co-catalyst is often used with the nitroxide radical primarycatalyst. The co-catalyst, if used, may be for example an alkali metalhalide or alkali earth metal halide. These may include alkali metalbromide, e.g. sodium bromide, and alkali metal chloride, e.g. sodiumchloride, and potassium chloride, alkali earth metal bromide, e.gcalcium bromide and magnesium bromide, alkali earth metal chloride, e.g.calcium chloride, and magnesium chloride.

Typically the co-catalyst is used from 0.01 to 10 mole %, preferably 0.1to 5 mol % equivalent based on amidoalcohol. Sodium tetraborate may beused in place of the bromide or chloride.

Solvent

The key to the invention resides in the selection of proper solvent,i.e., solvent which will partition into organic phase and aqueous phaseupon combination of oxidizing agent and amidoalcohol in the solvent.

Although the ideal solvents are at least partially water miscible (e.g.,tetrahydrofuran), the key is that, in the presence of oxidizing agent(e.g., aqueous sodium hypochlorite), at least two immiscible layers(e.g., a solvent-rich layer, normally the upper layer; and a water-richlayer, normally the lower layer) will form.

Without wishing to be bound by theory, applicants believe it isimportant that the amidoalcohol not be in the same phase as theoxidizing agent when combined. Applicants have found that this can beaccomplished in two different ways. According to claims a co-pendingapplication, this can be done by partitioning the final product(amidocarboxylic acid) into a liquid organic solvent (i.e., usingsolvent that will form two phases, rather than forming one substantiallyaqueous phase). The exposed amide group on the alcohol comprising amideis thus protected from cleavage (e.g., through attack by the bleachwhich has partitioned mainly into separate liquid aqueous phase), andconsequently far greater yield of carboxylic is produced. That is, it isimportant that, in the presence of the oxidizing agent, both a solventrich layer (substantially free of oxidizing agent) and an aqueous layer(comprising substantially of the oxidizing agent) form. It should benoted that how quickly the two phase separation occurs is dependentgenerally on the scale of the reaction. Typically, the phase separationwill occur in an hour or less, and can occur relatively instantaneously.

A second way (as claimed in the subject invention) to maintain theoxidizing agent and the alcohol in separate phases, in this case in aliquid water phase and in a solid phase, is to use water alone as thesolvent. The amidoalcohol is hydrophobic and does not dissolve ordisperse into the aqueous phase (it stays in solid phase), while theNaOCl remains in the continuous liquid aqueous phase.

A reaction in which the solvent will form only one liquid phase (e.g.,CH₃CN/water solvent used in JP 10/087,554), thus, is not suitable andwill form product in lower yield and purity.

Surprisingly, solvents at opposite extremes of the polarity scale may besuitable for the reaction. Suitable polar solvents may includeoxygenated hydrocarbons, more specifically cyclic and acyclic ethers andpolyethers. Suitable non-polar solvents may include cyclic and acyclicaliphatic solvents, and aromatic solvents.

Specific examples of cyclic oxygenated solvents (e.g. polar solvents)which may be used include tetrahydrofuren (THF) and dioxolane. Examplesof acyclic oxygenated solvents include 1,2-dimethoxyethane,dimethoxymethane, diethoxymethane, and 2-methoxyethyl ether.

It is preferred that the solvents do not contain anti-oxidants (e.g.,butylated hydroxyl toluene, abbreviated as BHT) as these anti-oxidantscan interfere with the oxidation reaction. Such anti-oxidants are oftenfound in cyclic and acyclic ethers and polyethers. Thus, preferably,solvents of the invention are substantially anti-oxidant free.

Specific examples of cyclic aliphatic solvents (e.g., non-polarsolvents) include cyclohexane; examples of acyclic aliphatic solventsinclude heptanes and hexanes; and examples of aromatic solvents includetoluene, o, m, or p-xylene, and mixed xylenes.

In preferred reaction, because of the consumption of oxidizing agent(e.g., sodium hypochlorite) and formation of carboxylic acid asconsequence of the reaction, sufficient base should be used in thereaction to maintain pH above 6, more preferred above 7, preferably 8-9.An example of base which may be used is alkali metal hydroxide (e.g.,NaOH).

The base may be added to the oxidizing agent before the oxidizing agentis added to the reaction or, alternatively, the base may be added, forexample, drop-wise during the course of the reaction as needed tomaintain constant pH.

The reaction itself typically takes place at room temperature, but isexothermic. Temperature rises of up to about 35° C. occur withoutcooling. A cooling bath can be used to reduce the exotherm.

A typical example of an oxidation of amonoethanolamide(N-lauroylmonoethanolamide, or MEA) to N-lauroylglycine(LG), as well as reaction conditions, isolation methology and rate ofconversion to LG are set forth below:

Reaction Conditions:

-   -   Solvent: Tetrahydrofuran (THF)/Water    -   Oxidizing agent: NaOCl (bleach, 11.5%, 3 eq.)+NaOH (base to        maintain pH)    -   Catalyst: KBr (co-catalyst), 4-Acetamido-TEMPO (abbreviated        AA-TEMPO)    -   Reaction temp: 25-30° C.    -   pH range: 12 (initial) to 6 (final)    -   Reaction time: 1-4 hr.    -   Isolation: THF extraction followed by solvent evaporation    -   Typical conversion rate: 95-99%

It should be noted that a mixture of N-lauroylglycine and sodiumN-laurylglycinate (e.g., salt form) can be obtained depending onisolation pH and therefore, yields can be calculated separately foreach.

EXAMPLES Protocol Extraction Technique to Isolate Carboxylic Acid (e.g.,N-laurylglycine)

At completion of oxidation reaction, reaction mixture is acidified to pHabout 3.0 (e.g., by addition of HCl) and layers are separated. Loweraqueous layer is extracted with THF and the combined THF layers areconcentrated on a rotary evaporator and dried in vacuo to givecarboxylic acid (e.g., N-lauroylglycine) as a white solid.

Extraction Technique to Isolate Alkali Metal or Alkaline Metal Salt ofCarboxylic Acid (e.g., Sodium N-Lauroylglycinate)

The reaction here is the same as above except THF layer is separatedwithout acidification. The aqueous layer must be in the range of 6-10,preferably 6-8. The aqueous layer is extracted (preferably twice) withTHF. Combined THF layers are concentrated on a rotary evaporator anddried in vacuo to yield the salt (e.g., N-lauroylglycinate)

Alternative Extraction Technique for the Carboxylic Acid

Besides THF extraction, carboxylic acid can be isolated by a drowningprocedure and filtration. In this procedure, the reaction mixture isacidified to pH about 2-3 and added to excess of water (about 3-4volumes compared to reaction mixture volume) with vigorous stirringusing a stirring paddle. Precipitate is collected by filtration, washedwith water and dried in vacuo to give carboxylic acid (e.g.,N-alkanoyl-glycine).

Reaction Monitoring of Cocoyl MonoEthylAmide (CMEA) Oxidation to CocoylGlycinate (CG) by HPLC

-   -   Instrument: Waters 2695 Separations Module equipped with a        Waters 2996 Photodiode Array Detector    -   Software: Empower Pro (version 5.00, Waters Corp.)    -   Column: Restek Pinnacle DB C18 5 um, 4.6×150 mm maintained at        30° C.    -   Flow Rate: 1 ml/min    -   Sample: 1-2 mg/ml in 1:1 water:acetonitrile (W:ACN) containing        0.04% acetic acid (AcOH)    -   Injection Vol: 15 uL    -   Mobile Phase: A=2 mM ammonium acetate, 0.04% AcOH        -   B=2 mM ammonium acetate, 0.04% AcOH 90% aqueous ACN    -   Gradient: 95:5 A:B to 100% B (gradient, 35 min) followed by 100%        B (isocratic, 5 min)    -   Detection: 205 nm

Example 1

Oxidation of N-lauroylethanolamide (LMEA) in THF with 6.5 eq. of NaOCl,and Acid Work-up. 33 mg (4.5 mol %) of KBr (co-catalyst) was dissolvedin 6 mL of water. Tetrahydrofuran solvent THF (31 mL), AA-TEMPO catalyst(25 mg, 2.5 mol %) and 1.5 g N-lauroylethanolamide (LMEA) were addedwith stirring to give a homogeneous water-white solution. Sodiumhypochloride oxidizing agent (22 mL of 11.5% aq. Solution, 6.5equivalents) and 2.3 mL of 2 NaOH (to maintain pH above 7) were mixed.The combined solution was added dropwise to the solution of LMEA andcatalyst over a period of 1.5 hour. A separate aqueous layer immediatelyformed upon addition of the sodium hypochlorite solution. The pH of theaqueous layer was 12.7 after addition of the first 3.5 ml. Thetemperature was maintained below 32° C. with an ice-water bath. Thereaction was stirred for 0.5 hr. more until complete conversion of LMEAto LG as determined by reversed-phase High Pressure LiquidChromatography, abbreviated HPLC. The pH at end of the reaction was 7.6.

At completion of the reaction, the mixture was acidified to pH 3.0 (toget the purified carboxylic acid) by addition of 8.5 mL of 1 N HCl, andthe layers were separated. The lower aqueous layer was extracted with 30mL THF, and the combined THF layers were concentrated on a rotaryevaporator and dried in vacuo to give N-lauroylglycine in 116% yield(residual water present).

Example 2

Oxidation of LMEA with 3.25 eq. of NaOCl, and Acid Work-up. Theprocedure in Example 1 was followed, except that the amount of sodiumhypochlorite was decreased to 3.25 equivalents. The isolated yield was103% (includes residual water), showing that the oxidation works withthe lower sodium hypochlorite amount.

Example 3

Oxidation of LMEA with 3.25 eq. of NaOCl, Isolation of Sodium Salt. Inthis example, sodium N-lauroylglycinate is obtained by a smallmodification of the isolation procedure. The procedure in Example 2 wasfollowed. The pH was 7.8 upon completion of the reaction. In this casethe THF layer was separated without acidification. The aq. layer wasextracted twice with 30 mL of THF. After extraction, the pH of the aq.layer was 8.3. The combined THF layers were concentrated on a rotaryevaporator and dried in vacuo to give sodium N-lauroylglycinate in 99%yield. Unlike N-lauroylglycine, the sodium N-lauroylglycinate dissolvesin water and affords a foam upon agitation.

Example 4

Oxidation of LMEA in THF with 6.5 eq. of NaOCl, Drowning Procedure atpH=2.6. The procedure of Example 1 was followed except for the isolationstep. After completion of the reaction, the mixture was acidified topH=2.6 with 9.25 mL of 1 N HCl. The entire reaction mixture (both THFand water phases) were poured in 240 mL of water with vigorous stirring.The precipitated product was isolated by gravity filtration, and washedwith 200 mL water. After air-drying, and further drying in vacuo, theproduct was obtained in 77% yield. The yield can be improved by betterfiltration techniques, e.g. by pressure filtration through a 0.45 μm orless filter.

Example 5

Oxidation of LMEA in THF with 3.25 eq. of NaOCl, Drowning Procedure,Effect of pH on Yield. The procedure of Example 2 was followed exceptfor the isolation step. After completion of the reaction, the mixturewas only partially acidified (to pH=5.2 with 3.6 mL of 1 N HCl.) Theentire reaction mixture (both THF and water phases) were poured in 240mL of water with vigorous stirring. The precipitated product wasisolated by gravity filtration, and washed with 240 mL water. Afterdrying in vacuo overnight, the product was obtained in 59% yield (basedon free carboxylic acid), and 55% (based on the sodium carboxylate). Thelower yield than Example 4 is attributed to the larger proportion of thewater-soluble sodium carboxylate at the higher pH.

Example 6

Oxidation of LMEA with 3.25 eq. of NaOCl in Water, Acid Work-up. KBr (33mg, 4.5 mol %) and M-TEMPO (25 mg, 2 mol %) were dissolved in 50 mLwater. 1.50 g LMEA was added and the mixture stirred 1.5 hr. to form ahomogeneous suspension. Dilute sodium hypochlorite (5%) was added in 2.0mL increments over 1.3 hr. After each addition, 0.1 N HCl was added, ifnecessary to maintain a pH of 8-9. Details of the addition are given inthe Table below:

5% NaOCl (mL) 0.1 N HCl pH 0.0 — 6.5 2.0 3.4 8.6 4.0 1.8 8.5 6.0 1.1 8.58.0 0.6 8.5 10.0 1.0 8.5 12.0 0.4 8.5 14.0 — 8.5 16.0 — 8.2 18.0 — 8.120.0 — 8.0 22.0 — 8.0 25.0 — 8.0

After stirring for 20.5 hr., the pH dropped to 5.9. The mixture was atranslucent white emulsion. It was brought to pH=3.0 by addition of 3.5mL of 1 N HCl, and extracted twice with 75 mL of THF. The combined THFlayers were concentrated on a rotary evaporator and further dried invacuo to give 1.81 g of N-lauroylglycine in 114% yield (includesresidual water).

Example 7

Oxidation of N-Cocoylmonoethanolamide (CMEA) with 3.25 eq. of NaOClusing Toluene as Solvent, Acid Work-up. The oxidation reaction works onmixtures of monoethanolamides as well, including those derived frommixtures of fatty acids occurring in nature. In this example,N-cocoylmonoethanolamine (a mixture of C-8, C-10, C-12 (majorcomponent), C-14, C-16, and C-18 monoethanolamides) was oxidized undersimilar conditions to give a mixture of the correspondingN-cocoylglycines. KBr (33 mg, 4.5 mol %) and AA-TEMPO (25 mg, 2 mol %)were dissolved in 6 mL of water. CMEA (1.50 g, 6.16 mmol assuming 100%LG) was dissolved 60 mL toluene at 32° C., and the solution added to theKBr and M-TEMPO. The stirred mixture was maintained at 31-37° C. duringthe course of the addition and hold period. A solution of sodiumhypochlorite (11 mL of 11.5% aq. solution, 3.25 eq.) and 1.15 mL of 2 NNaOH was added in 2.0 mL increments over a period of 50 min. The pH was6.9 at the end of the addition. After 40 min. at 33° C., the pH wasadjusted to 8.6 with 0.5 mL of 1 N NaOH. Stirring was continued for anadditional 3.5 hr. and then the solution was allowed to cool to roomtemperature.

The gelatinous reaction mixture was diluted with 70 mL THF and broughtto pH=2.2 with 5.5 mL of 1 N HCl. The layers were separated, and the aq.layer were extracted with an additional 20 mL THF. The combined THFlayers were concentrated on a rotary evaporator and dried in vacuo togive of N-cocoylglycine in 84% yield.

Example 8

Oxidation of N-Cocoylmonoethanolamide (CMEA) with 3.25 eq. of NaOClusing Cyclohexane as Solvent, Acid Work-up. The procedure of Example 4was followed, except that the CMEA was dissolved in 120 mL cyclohexaneat 43° C. instead of toluene. After the reaction a translucent emulsion(pH=6.2) was obtained. The emulsion was brought to pH 3.1 with 3.0 mL of1 N HCl, and extracted twice with 100 mL THF. The combined THF layerswere concentrated on a rotovap and dried in vacuo to giveN-cocoylglycine in 73% yield.

Comparative Example

To show that correct solvent is required, applicants conducted anexperiment comparing the reaction for production ofN-lauroylmonoethanolamine as set forth in Example 5 in Japanese patentapplication Ser. No. 10/087,554 (Assigned to Lion Corp.) to the reactionof our invention. Results are set forth below.

Process Parameter JP 10/087,554 Our Invention Conc. of Oxidant 5% (0.8M) NaOCl 11.5% (1.85 M) NaOCl Amount of Oxidant 2.8 eq. NaOCl 3.25 eq.NaOCl Solvent Acetonitrile THF Phases Acetonitrile was dissolved in2-Phase System: Separate water and only one liquid THF and aqueouslayers. phase formed Two liquid phases were present Location of LMEALMEA undissolved in LMEA dissolved in THF CH₃CN/water - thick slurrylayer. was obtained. Added base No NaOH added to NaOCl 2 N NaOH added toNaOCl pH Range pH 5.5–6.6 during reaction pH 13.2–7.4 during reactionReaction Temperature 33–35° C. 24–26° C. Reaction Time 6 hr. includingNaOCl addition 2 hr. including NaOCl time addition time. Isolated Yield81% >100% (water present) Purity (HPLC Area %) 30.6% 68.5%

Summary of Oxidation Examples

A summary of the Examples for oxidation of LMEA to LG is set forth inthe Table below.

Reac Initial Peak Work- Yield Ex. NaOCl Time Temp Temp Initial FinalIsolation up as Yield No NaOCl:Substrate Conc. Solvent (hr.) (° C.) (°C.) pH pH Method pH Acid as Salt 1  6.5:1 11.5% THF 2 24 32 12.71 7.57THF 3.0 116% 107% Extraction 2 3.25:1 11.5% THF 2 24 26 9.89 7.61 THF2.1 103% 95% Extraction 3 3.25:1 11.5% THF 2 25.4 26.9 10.3 7.8 THF 8.3108% 99% Extraction 4  6.5:1 11.5% THF 2 24.8 30.2 11.56 7.24 Water 2.677% 71% Drowning 5 3.25:1 11.5% THF 3 23 25.2 10.35 — Water 5.2 59% 55%Drowning 6 3.25   5% Water 21^(a  ) 19.5 19.5 8.56 7.81 THF 2.5 114%105% Extraction ^(a)Actual reaction time may be less.

A summary of the Examples of the oxidation of N-cocoylmethanolamide toN-cocoylglycine is set forth in the Table below.

Reac Initial Peak Yield Yield Ex. NaOCl Time Temp Temp Initial FinalIsolation Work- as as No NaOCl:Substrate Conc. Solvent (hr.) (° C.) (°C.) pH pH Method up pH Acid^(b) Salt^(b) 7 3.25:1 11.5% Toluene  6^(a)31 38 — 8.9 THF 2.2 84% 78% Extraction 8 3.25:1 11.5% Cyclohexane 16^(a)38.5 41 — 6.2 THF 3.1 73% 67% Extraction ^(a)Actual reaction time may beless. ^(b)Assume CMEA and CG are each the corresponding 100% C-12compounds.

1. A process for converting an alcohol comprising amide group tocorresponding carboxylic acid in yield ≧75% which process comprisesreacting amidoalcohol:R¹—CONR²(CH₂)_(m)OH wherein R¹ is linear or branched alkyl or alkenylgroup having 7 to 22 carbon atoms; R² is H, an alkyl or hydroxyalkylgroup with 1 to 6 carbon atom(s); and m is an integer from 1 to 6, withan oxidizing agent in the presence of a hindered nitroxide radical,solvent, and optional co-catalyst, wherein the solvent is solely waterand wherein, in the presence of the oxidizing agent, the compositionseparates into layers comprising (1) water layer which comprisessubstantially the oxidizing agent and (2) a solid organic layersubstantially free of qxidizing agent into which amidoalcohol stays orpartitions wherein said separation permits said yields of ≧75%.
 2. Aprocess according to claim 1, wherein the alcohol comprising amide groupis an alkanoylmonoalkanolamine.
 3. A process according to claim 2,wherein the alkanoylmonoalkanolamine is lauroyl monoalkanolamide orcocomonoethanolamide.
 4. A process according to claim 1, wherein theoxidizing agent is selected from the group consisting of chlorine, ahypochlorite, chloroisocyanuric acid and mixtures thereof.
 5. A processaccording to claim 1 wherein the oxidizing agent is selected from thegroup consisting of NaOBr, bromosuccinimide, bromoisocyanuric acid,peracids, oxone, H₂O₂ and mixture thereof.
 6. A process according toclaim 1, wherein oxidizing agent is present in amount from equimolar to8 molar.
 7. A process according to claim 1, wherein the nitroxidecatalyst is 4-acetamido-TEMPO.
 8. A process according to claim 1, where,in addition to hindered nitroxide radical co-catalyst is used.
 9. Aprocess according to claim 8, wherein co-catalyst is alkali metal halideor alkali earth metal halide.
 10. A process according to claim 1,wherein solvents contain substantially no oxidizing agent.
 11. A processaccording to claim 1 where base is additionally added to the reaction.12. A process according to claim 1 wherein sufficient base is added tomaintain pH above 6.